In a particular application, the liquid is of the gel or cream type, for example for use in cosmetics or for pharmaceutical treatments.
Pumps having the following properties are known:                sealed closure of the ejection orifice in order to limit contact between the external air and the liquid stationary in the pump, in particular to prevent drying and/or degradation of said liquid over time;        absence of contact between the liquid and metallic parts in order to prevent any physical and chemical degradation of the liquid;        absence of passage for taking up air in the bottle in compensation for the product rendered.        